The Prognostic Potential of Opto-acoustic Imaging in Patients with Breast Cancer
A new imaging modality may offer a wealth of prognostic information on tumor behavior and differentiation of cancer subtypes.
Opto-acoustic imaging (OA), an exciting new means of illuminating vascular properties of tumors and surrounding tissues, promises to be a clinical staple for evaluation and management of patients with breast cancer. Currently in the FDA premarket process, OA technology offers the sensitivity of ultrasound imaging and the specificity of light imaging, rendering it a unique means of noninvasively assessing masses before, or in lieu of, biopsy. Ultimately, it may also provide a wealth of prognostic information on tumor behavior, such as aggressiveness and probability and timing of metastasis.
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OA employs functional optic and real-time acoustic visibility to provide this rich store of visual evidence and data. Stephen Grobmyer, MD, Director of Breast Cancer Surgery at Cleveland Clinic Cancer Center, explains that current imaging technology we use “essentially just determines the existence of a lump.” With OA imaging, “the physician scans the tumor area from different angles, from which he gleans real-time information about tumor physiology.” The captured images elucidate the vascularity outside the tumor as well as inside, enabling visibility into the orientation of the blood vessels and the oxygenation and deoxygenation of the blood.
“Instead of just looking at tumor cells through a microscope, with OA we can evaluate information about the tumor morphology and physiology that was never before accessible to us. Examining this morphology of the tumor, versus just the tumor cells themselves, may prove to be highly prognostic,” says Dr. Grobmyer.
OA imaging may also challenge the traditional biopsy as the post-screening next step in diagnosis. Up to 75 percent of breast biopsies are benign. Yet a study by Neuschler et al. of over 2,000 cases, shared at the 2017 RSNA conference, demonstrated that negative biopsies could be cut by about half if OA is used to examine the tumor. Dr. Grobmyer foresees procedural benefits for patients and physicians alike. “With OA, we can potentially avoid putting our patients through the discomfort of breast biopsy, the scarring from the biopsy and the anxiety associated with waiting for results.”
Using the Imagio® OA/US breast imaging system, Dr. Grobmyer coauthored a study that supports OA’s viability as a differentiator between some tumor types. The study’s aim was to determine the relationship between OA attributes and pathologically-determined prognostic markers (PDPM) in the four primary types of malignant tumors: luminal A (LA), luminal B (LB), human epidermal growth factor receptor 2 (HER2) and triple negative (TN).
In this study, independent breast pathologists used images from the Imagio OA/US at 22 clinical sites to score internal (nidus) and external (boundary and periphery) features of 655 invasive and 22 DCIS tumors. These scores were then reviewed by an experienced central breast pathologist blinded to the OA assessment. Identification of tumor ER, PR and HER2-neu expression was performed through immunohistochemistry.
Dr. Grobmyer’s team conducted a two-way analysis of variance (ANOVA) and Tukey HSD (honest significant difference) test for pairwise comparisons. All statistical testing was done at a 5 percent significance level.
Findings of significant correlations with PDPM were robust between three of the six possible pairings: LA and LB, LA and HER2, and LA and TN. Differentiation relative to LA tumors was the common denominator in these findings. There were no significant correlations between the PDPM and scorers’ assessments in the comparisons of LB and HER2, LB and TN or TN and HER2.
From the results of this study and other research conducted to date, Dr. Grobmyer expects clinicians and researchers will quickly recognize the potential of this safe, painless and real-time imaging. “I suspect we are at the infancy of this technology. But as the value of visualizing and describing tumor vascularity becomes recognized for both diagnosis and treatment, I believe OA has the potential to really change how we approach the care of patients.” He continues, “There is no precedent for an imaging technology that discriminates between various kinds of BC. And that capability may just be the tip of the iceberg.”